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    <div class="example" id="panic">
      <h2><a href="./">Go by Example 中文版</a>: Panic</h2>
      
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            <p><code>panic</code> 意味着有些出乎意料的错误发生。
通常我们用它来表示程序正常运行中不应该出现的错误，
或者我们不准备优雅处理的错误。</p>

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            <a href="http://play.golang.org/p/r3gi7bMcWdc"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
          <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>

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          <div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;os&quot;</span>
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          <div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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            <p>我们将使用 panic 来检查这个站点上预期之外的错误。
而该站点上只有一个程序：触发 panic。</p>

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          <div class="highlight"><pre>    <span class="nb">panic</span><span class="p">(</span><span class="s">&quot;a problem&quot;</span><span class="p">)</span>
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            <p>panic 的一种常见用法是：当函数返回我们不知道如何处理（或不想处理）的错误值时，中止操作。
如果创建新文件时遇到意外错误该如何处理？这里有一个很好的 <code>panic</code> 示例。</p>

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          <div class="highlight"><pre>    <span class="nx">_</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Create</span><span class="p">(</span><span class="s">&quot;/tmp/file&quot;</span><span class="p">)</span>
    <span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
        <span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
    <span class="p">}</span>
<span class="p">}</span>
</pre></div>

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            <p>运行程序将会导致 panic：
输出一个错误消息和协程追踪信息，并以非零的状态退出程序。</p>

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          <div class="highlight"><pre><span class="gp">$</span> go run panic.go
<span class="go">panic: a problem</span>
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          <div class="highlight"><pre><span class="go">goroutine 1 [running]:</span>
<span class="go">main.main()</span>
<span class="go">    /.../panic.go:12 +0x47</span>
<span class="go">...</span>
<span class="go">exit status 2</span>
</pre></div>

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            <p>注意，与某些使用 exception 处理错误的语言不同，
在 Go 中，通常会尽可能的使用返回值来标示错误。</p>

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